Why You’ll Love This Recipe

I love this recipe because it brings together two of my favorite chocolate desserts in one irresistible treat. The dense brownie base satisfies my chocolate cravings, while the smooth mousse adds a luxurious, creamy contrast. It’s perfect for birthdays, holidays, or whenever I want to impress without making a complicated layered cake. Plus, it slices beautifully and looks stunning on a dessert plate.

ingredients

(Here’s a tip: Check out the full list of ingredients and measurements in the recipe card below.)

For the brownie layer:

Unsalted butter
Granulated sugar
Eggs
Vanilla extract
All-purpose flour
Unsweetened cocoa powder
Salt
Semi-sweet or dark chocolate chips (optional for extra richness)

For the chocolate mousse layer:

Semi-sweet or dark chocolate, chopped
Heavy cream (divided: for melting and for whipping)
Powdered sugar (optional, for a sweeter mousse)
Vanilla extract

For topping (optional):

Shaved chocolate or cocoa powder
Whipped cream
Fresh berries or mint leaves

directions

I preheat the oven to 350°F (175°C) and line an 8×8-inch baking pan with parchment paper.
To make the brownies, I melt butter in a saucepan or microwave-safe bowl, then stir in sugar, eggs, and vanilla.
I add flour, cocoa powder, and salt, stirring until just combined. I fold in chocolate chips if using, then spread the batter into the prepared pan.
I bake for 20–25 minutes or until a toothpick comes out with moist crumbs. I let the brownies cool completely in the pan.
For the mousse, I melt chopped chocolate with a small amount of cream over low heat or in the microwave until smooth, then let it cool slightly.
In a separate bowl, I whip the remaining cold heavy cream with vanilla and a bit of powdered sugar (if using) until soft peaks form.
I fold the whipped cream gently into the cooled melted chocolate until fully combined and fluffy.
I spread the mousse over the cooled brownie layer and smooth the top.
I refrigerate for at least 2 hours, or until set, before slicing into squares. I garnish with chocolate shavings or whipped cream if I want to dress them up.

Servings and timing

This recipe makes about 9 large or 12 smaller squares. It takes about 20 minutes to prep, 25 minutes to bake, and 2 hours to chill—so I plan for roughly 3 hours from start to serve.

Variations

Sometimes I add espresso powder to the brownie layer for a mocha twist or a splash of liqueur (like Bailey’s or Kahlúa) to the mousse for a grown-up flavor. I’ve also made a peanut butter mousse instead of chocolate for a different layered combo. For a festive touch, I swirl raspberry jam into the brownie batter or top the finished bars with crushed peppermint during the holidays.

storage/reheating

I store these brownies in the fridge in an airtight container for up to 4 days. They taste best chilled or at room temperature. I don’t reheat them—they’re meant to be served cold. I can freeze them as well, individually wrapped, for up to 2 months. I just thaw them in the fridge overnight before serving.

FAQs

Can I use a boxed brownie mix?

Yes, when I’m short on time, I use a boxed mix for the brownie layer and focus on making the mousse from scratch.

How do I keep the mousse light and airy?

I fold the whipped cream into the chocolate gently to avoid deflating the mousse. I also make sure the chocolate mixture is cool but still fluid before combining.

Can I make this dessert ahead?

Definitely. I often make it a day ahead and let it chill overnight. It holds up beautifully and tastes even better the next day.

Is this dessert very sweet?

It has a balanced sweetness—rich and chocolaty without being overly sugary. I adjust the powdered sugar in the mousse to taste.

What kind of chocolate works best for the mousse?

I use a good-quality semi-sweet or dark chocolate bar for the best texture and flavor. Chocolate chips can work, but bars melt more smoothly.

Conclusion

Chocolate Mousse Brownies are a dreamy, decadent treat that never fails to impress. The combination of rich brownie and airy mousse creates a perfect contrast in every bite. Whether I’m serving it for a party or sneaking a piece with my afternoon coffee, this dessert always feels like a little luxury.